Want to BOOST Your Mood? The Surprising Role of Gut Health

A 166,000-person study followed participants for multiple years and found that those eating an anti-inflammatory Mediterranean-pattern diet had lower dementia rates and a larger hippocampus. Mark Hyman's clinical experience: 'if you are effective enough by using a big enough lever — in other words dramatically changing the diet enough — you'll see changes in literally days.' Austin Perlmutter notes the MIND diet (Mediterranean-DASH hybrid specifically targeting neurodegeneration) as a close cousin with robust dementia-prevention data. The mechanism goes beyond antioxidants: polyphenols in herbs, spices, coffee, and buckwheat appear to change epigenetic expression in immune cells.

Mark Hyman describes a 9-year-old girl who was violently aggressive, kicked out of class multiple times daily, stopped buses on the way home with her behavior. 'I screened her for her gut health and looked at her urinary organic acids and looked at the microbiome and turned out she had severe elevations of biomarkers for bacterial overgrowth in the gut for yeast overgrowth. I literally gave her an antibiotic and an antifungal and like boom overnight she was a different person — a perfectly behaved sweet little 9-year-old girl.' This is not an isolated phenomenon: hepatic encephalopathy (where liver failure allows gut bacterial toxins to reach the brain) has been understood for decades in conventional medicine, yet its implication for non-liver-failure gut-brain disease has not been generalized.

Austin Perlmutter: 'stress seems to take the prefrontal cortex offline which is why if you are stressed you're more likely to eat junk food. Similarly if you're sleep deprived this connection becomes a little bit less concrete — it helps explain why people who are sleep deprived have trouble making healthy choices. They tend to eat a lot more food and they eat a lot more junk food.' Mark Hyman: 'I don't see [it] clearly — I want sugar, carbs, give me the cookies and ice cream — and I've written books all about why not to eat that. I still want it.' Inflammation as a sleep driver means the gut microbiome influences sleep quality — establishing a triadic loop: poor diet leads to dysbiosis leads to neuroinflammation leads to poor sleep leads to worse dietary choices.

Austin Perlmutter: 'your brain is a reflection of the inputs you give it. Of course it's what you put into your mouth... it's also what you inhale... and the piece that many people don't pay enough attention to is what you consume through your eyes and through your ears.' Mark Hyman: 'the media that we now mostly consume whether it's news or social media is basically like junk food for the brain — it's highly addictive, no nutrients, it activates anger and activates your primitive limbic brain, your amygdala, your dopamine activation — you end up in this vicious cycle of addiction.' The corporate incentive structure actively exploits this: marketing to children via fMRI studies, gambling app design, and addictive food formulation are all monetizing the same amygdala-hijacking pathway.

Mark Hyman explicitly names exercise as one of the tools in preventive neurology alongside diet and sleep: 'we have to sleep, we have to deal with stress, we have to exercise — all that's given — and we have to fix our microbiome.' He draws a direct parallel to preventive cardiology: 'we take so much time now to think about preventive Cardiology — you should be jogging each day to decrease your risk of heart attack — what are we doing each day to prevent depression, to prevent anxiety, to prevent Alzheimer's disease?' The framing is brain-first: exercise is not primarily a body composition tool but a brain immune system modulator.

Austin Perlmutter: 'to that end the important piece is to look at the data that we have available — that can be everything from waist to hip ratio, hemoglobin A1c, potentially things like zonulin, insulin resistance — these are for inflammation in the body and they correlate with risk for neuroinflammatory diseases.' Zonulin is a marker of gut permeability triggered by gluten in susceptible individuals — elevated zonulin signals leaky gut, which is a precursor to elevated systemic LPS. This panel gives a practical window into neuroinflammatory risk without requiring advanced imaging.

Austin Perlmutter explains the Big Bold Health research platform: 'certain diets correlate with certain immune states. What we didn't know is why. The mechanism that we're looking at here is through epigenetics — by changing the way the DNA is being used.' The sprouting process increases polyphenol concentration while reducing digestive antinutrients. Mark Hyman: 'herbs and spices are actually some of the most concentrated sources of polyphenols — these are natural anti-inflammatories, and we also know coffee which is one of my personal favorites.' The principle is the xenohormesis hypothesis: plants grown under stress (high altitude, cold, poor soil) produce higher concentrations of defensive polyphenols, which exert health-promoting effects when consumed.

Austin Perlmutter notes: 'roughly 50% of people will get a substantial improvement [on antidepressants], roughly 33% of people will get actual remission.' That means two thirds of patients with major depression do not reach remission on the current first-line treatment. The serotonin debunking paper compounds this — we have a first-line treatment built on an unproven mechanism that fails most patients. The inflammation hypothesis offers a mechanistic explanation (elevated serum inflammatory markers in depressed patients) that points toward entirely different interventions.

Austin Perlmutter explains: 'a microglia cell is a bona fide immune cell that lives in the brain. Its role is not just to protect the brain against outside threats but it's actually an immune cell that modulates how neurons fire, how they work.' When microglia are activated by LPS from gut bacteria, or by chronic stress, poor sleep, air pollution, or ultra-processed food, they shift into a pro-inflammatory state that disrupts prefrontal cortex connectivity and amplifies amygdala reactivity. Interestingly, research suggests that microglia state may also predict personality traits — and psychedelics appear to shift microglia toward a more open, anti-inflammatory phenotype.

Austin Perlmutter: 'it is very likely that the immune status of the mom is able to speak to the children by way of placental transfer. It seems like it might modify epigenetics, it seems like it might speak to microglia cells.' This means the junk food diet, sedentary lifestyle, and chronic stress that inflame today's population are already programming the brains of the next generation. The effect is invisible for a decade — the ADHD diagnosis arrives at age 10, masking its origin in prenatal inflammation.

Mark Hyman: 'there's randomized human clinical trials for example the smiles trial they looked at basically diet and anti-depressants and it was basically as effective if not better than antidepressants if you ate a whole food diet.' And: 'the FINGER trial looking at Alzheimer's a multimodal intervention using lifestyle interventions, dietary interventions, optimizing biomarkers actually reversed cognitive decline in Alzheimer's patients — something that doesn't actually happen and doesn't — there's no drug that does that.' These trials represent a paradigm shift that has not yet been translated into clinical psychiatry or neurology practice.

Austin Perlmutter: 'PM 2.5 exposure correlated with not just any crime but violent impulsive crime. That's important — this isn't premeditated stuff. What we're talking about is that it changes people's brains such that they're more likely to do things like hurt another person.' The same mechanism (impaired prefrontal cortex, hyperactive amygdala) explains why prison nutrition interventions show dramatic results: giving violent prisoners healthy food produced a 56% reduction in violent crime; adding a multivitamin drove it to 80%. A juvenile detention study saw a 97% reduction in bad behavior, 75% reduction in restraints, and 100% reduction in suicides.

Mark Hyman: 'there's a whole field of what we call psychobiotics right which are probiotics that have effect on mood and depression anxiety sleep. I'm trying one now which is basically a sleep probiotic that's supposed to increase deep sleep.' The Austin Perlmutter framing is mechanistic: gut immune cells sample bacterial composition and transmit signals through the bloodstream and vagus nerve to microglia, which in turn regulate neuronal firing patterns. The microbiome is therefore an upstream modulator of the entire brain immune state.

Austin Perlmutter explains the research: 'when people's immune systems are aging faster — in the group of people who are getting older in their immune system more than others — it actually slows the rate of aging when people are taking these polyphenols that are found in Himalayan Tartary Buckwheat.' The sprouted version is roughly 4x more concentrated in polyphenols than the raw grain version because sprouting elevates rutin and quercetin levels while reducing antinutrients. Mark Hyman discloses being an advisor and investor in Big Bold Health.